Siemens SIMATIC ET 200SP Manual page 30

S7-300/400 or a different CPU
The module generates a hardware interrupt at the following events:
● At rising edge (signal change from 0 to 1)
● At falling edge (signal change from 1 to 0)
If an interrupt occurs, a corresponding interrupt OB is called in the CPU of the IO controller.
You will find detailed information on the event in the hardware interrupt organization block
with the "RALRM" (read additional interrupt information) instruction and in the STEP 7 online
help.
The channel of the module that triggered the hardware interrupt is entered in the start
information of OB40 in the OB40_POINT_ADDR tag. The following figure shows the
assignment to the bits of double word 8 in local data.
Figure 3-6
Structure of the additional interrupt information
Table 3- 7 Structure of USI = W#16#0001
Data block name
USI
The channel that triggered the hardware interrupt follows.
Channel
It follows the error event that triggered the hardware interrupt.
Error event
Digital input module DI 8x24VDC HS (6ES7131-6BF00-0DA0)
Equipment Manual, 11/2019, A5E35243810-AD
OB40_POINT_ADDR tag
Content
W#16#0001
B#16#00 to B#16#07
B#16#01
B#16#02
3.3 Interrupts/diagnostics alarms
Comment
User Structure Identifier: Additional interrupt
info for hardware interrupts of the I/O module
Channel 0 to 7 of the I/O module
Rising edge
Falling edge
Operating mode DI
Bytes
2
1
1
29